Clinical Significance of Murmurs at the 2nd Sternal Border

Anatomic Localization and Murmur Characteristics

The American College of Cardiology notes that the 2nd sternal border corresponds to two critical auscultatory areas: the aortic valve area at the right 2nd intercostal space and the pulmonic valve area at the left 2nd intercostal space 1, 2
The American Heart Association indicates that innocent pulmonary systolic murmur is the most common benign cause, characterized by a medium-pitched, harsh character heard at the left middle and upper sternal border, which disappears with upright position 3, 4
The American College of Cardiology recommends that venous hum, a medium-pitched, blowing character at the right or left upper sternal border, be differentiated by its disappearance with jugular venous compression or supine position 3, 4

The American College of Cardiology states that aortic stenosis is characterized by a midsystolic crescendo-decrescendo murmur from outflow obstruction at the right 2nd intercostal space, with associated findings including soft or absent A2 and reversed splitting of S2 indicating severe disease 1, 2
The American Heart Association notes that pulmonic stenosis is characterized by a midsystolic murmur at the pulmonic area and left sternal border, with an ejection sound heard only during expiration at the pulmonic area 1, 2
The American College of Cardiology indicates that atrial septal defect is characterized by a grade 2/6 midsystolic murmur in the pulmonic area and left sternal border, with fixed splitting of S2 during both inspiration and expiration being pathognomonic 1, 2

The American College of Cardiology recommends that positional changes, such as standing or supine position, be used to differentiate innocent from pathologic murmurs, with innocent murmurs typically disappearing or decreasing with standing 1, 2, 3, 4
The American Heart Association notes that respiratory variation, with right-sided murmurs increasing with inspiration and left-sided murmurs increasing with expiration, provides crucial diagnostic information 1, 2
The American College of Cardiology states that specific maneuvers, such as jugular venous compression or bilateral shoulder hyperextension, can be used to eliminate venous hum or carotid bruit 3, 4

The American College of Cardiology recommends that echocardiography be ordered when red flag features are present, including abnormal S2, or when a specific innocent murmur cannot be confidently identified 1, 2
The American Heart Association indicates that echocardiography is also warranted in patients with symptoms, such as dyspnea or chest pain, or in those at risk for valve disease 1, 2